Uddin, Md. Jashim Marnett, Lawrence J. Synthesis of 5- and 6-Carboxy-X-rhodamines An efficient route is reported to 5- and 6-carboxy-X-rhodamines (compounds <b>1</b> and <b>2</b>) that contain multiple <i>n</i>-propylene or γ,γ-dimethylpropylene groups bridging terminal nitrogen atoms and the central xanthene core. Gram quantities of these dyes are synthesized from inexpensive starting materials. The isolated products are activated by selective transformation of the carboxylic acid group into <i>N</i>-hydroxysuccinimidyl esters in situ and then conjugated with an amino group of a molecule of interest. carboxylic acid group;terminal nitrogen atoms;compounds 1;Gram quantities;xanthene core 2015-12-16
    https://acs.figshare.com/articles/journal_contribution/Synthesis_of_5_and_6_Carboxy_X_rhodamines/2010993
10.1021/ol801904k.s001